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A Quantum Carol

Difficulty

by Helsen, Kroll, Rol and van Dam

The phone was ringing in the lab, Sophie let it ring a few times before looking up from her experiment. She was a bit annoyed until she realized what time it was, almost midnight and she had only just got the experiment running. She picked up the phone, half expecting to hear her advisor when she heard her mother’s voice:

“Sophie, we were worried about you, you didn’t pick up your phone and it has been almost four hours!”.

“Don’t worry Mom, I’ll be right there, I just have to set up a measurement run overnight, otherwise the experiment will be doing nothing over Christmas!”

“But dear, like you said, it’s Christmas, you promised you’d be here! You know how Granny has been looking forward to seeing you.”

“OK, OK I’ll just start what I have now, but I still have to refill the traps. I’ll be there in 10 minutes”, she said as she hung up the phone.

As the nitrogen traps overflowed, a haze covered the floor and she started to feel a bit dizzy…

The Ghost of Quantum Past

Suddenly she felt of a cold touch on her shoulder. When she looked behind her the lab was gone and she was standing in a large lecture hall. She saw a man with a lion’s mane standing in front of a blackboard.

“On the program it says this is a keynote speech–and I don’t know what a keynote speech is.”

He then proceeded to lay out the idea of using physics to simulate physics, an idea so obvious in retrospect that it seems surprising that it took decades before people realized how extremely useful this could be. Sophie couldn’t help but notice how inspired all these theorists were with these ideas, but also how far removed this idea was from her daily experiences in the lab. She was still struggling to get her individual qubits to do what she wanted, let alone put them all together to simulate a room temperature superconductor.

She raised her hand to ask a question and to her surprise he looked straight through her. He continued talking about quantum mechanics, about how trying to control individual particles used to be absurd, a philosophical curiosity, but today people are experimenting with methods that can sense individual atoms. There is nothing fundamental that prevents us from choreographing the dance of large ensembles of individual particles in minute detail, he stressed. Annoyed, she raised her hand and waved at him.

“Annoying isn’t it, when they can’t see you.”

Startled she looked aside and saw three ghosts. The first was Richard Feynman, who at the same time was delivering the keynote that was not a keynote.

“The reason I took you here Sophie, is to show you where it all started and to share with you the dreams we had.”

“But also, to introduce you to Andrea and Steve. ”

Andrea looked a bit too stiff for her tastes, an obvious academic not entirely comfortable with her transition to industry, quite reminiscent of her own advisor.
She had a bit more trouble placing Steve, who seemed only a few years older than her but looked nothing like a typical PhD student with his beanie and his goggles.

The Ghost of Quantum Present

A dark haze quickly filled the room, and Sophie felt some hands gently land on her shoulders and guide her away. A voice beside her said,

“I am the ghost of the quantum present. My name is Andrea, and if you don’t recognize me that is not so surprising. I’m not real, more of an amalgam of your subconscious – regardless, I am here to try and show you something you know but have not yet realised.”

A new scene faded into view. It was Sophie’s very own lab, just a few days ago. People were milling about giant refrigerators while racks of computers merrily bleeped away. It was right before the Christmas break so people were working feverishly trying to get as much work done as possible before taking some well needed rest. However, this wasn’t the only source of activity, in the back Sophie’s professor was showing a group of important looking people in suits his lab space. The people looked impressed as he expounded on how quantum computing was going to change the world forever.

“See this is exactly what I mean,” said Sophie. “We are promising these people the world, and they are buying every second of it but none of it is there yet, and we don’t know for sure if these quantum computers will even work as advertised.”

Sophie had said it more angrily than she meant to, luckily the people around here couldn’t hear nor see her.

“But you see” said the Ghost of Quantum Present, “It’s like this with any new technology. First people dream of something new, something grand. And then when the time comes to actually build it, they sometimes get a little ahead of themselves. But it usually turns out alright in the end.”

“But it’s all just hype!” Sophie sneered, “Think about it. We don’t even know if the error correction schemes we have right now will actually work. Sure they work in theory, but there are all kinds of assumptions that may not be validated in a real quantum computer. And then even if they do eventually work, how do we know that we’ll actually be able to solve all of the problems we say we can solve? Making high temperature superconductors is going to be complicated even with a real quantum computer”

“Sure”, answered the Ghost, “But this is always the case with new technologies. When people started building classical computers half a century ago they couldn’t possibly foresee where they would end up, and what applications would actually turn out practical. We didn’t end up getting flying cars, but we got the internet instead. And it’ll be the same with quantum computers.”

Sophie grumbled. “Color me skeptical” she said.

She fell silent and stared intently at a particularly complicated looking rack of equipment. Suddenly she felt another cold touch on her shoulder.

“Maybe I can be of help”, said the Ghost of Quantum Future, with the uncharacteristic beanie and goggles. “Allow me to lift up the curtain a little bit and show you a glimpse of the future.”

The Ghost of Quantum Future

Sophie saw her own lab disappearing momentarily in wave of mist. Two big doors appeared in front of her. She took a deep breath and moved to push against the doors; they slided open immediately before she had the chance. Quietly she entered the room, hoping not to be noticed by the many people working there, staring at their screens.

In the background hulked what was probably the biggest cryostat refrigerator she had ever seen. A quiet hissing emanates from the giant machine and a bewildering variety of lights flickered on and off.

“Pretty cool eh?” said the Ghost of Quantum Future, walking up behind her.

“Cool? This is amazing, this is so much more advanced than anything we’ve ever dreamed of.”

Sophie let her hand run over an exposed cable the size of her thigh. She was genuinely impressed.

“Yeah, it turns out that people can build some pretty crazy stuff if you give them the time and the resources,” said the Ghost.

“So what kind of calculations do they do here?” Sophie’s inner scientist tore through her previous cynicism and she spoke with unabashed enthusiasm. “Have they learned how to make high temperature superconductors? What about curing cancer?”

The Ghost snickered a little. “Oh no,” he said, “those turned out to be way harder than people originally thought. But they are doing some really great other stuff with it! You should see the size of the cables that connect this thing to the rest of the internet.”

“You mean this thing runs on the net?” Sophie was really excited now.

“Oh yeah, people are logging in all the time. Sending Schrodinger cat pictures to each other. Okay that was mostly a joke.” He chuckled: “Turns out that if you give people a big enough quantum computer, a lot of them come up with uses for it you wouldn’t believe! For instance they made this…” as he wildly gestured towards one of the computer screens where a complicated visualisation showed an intricate dance of coloured shapes arranging and rearranging themselves.

“Ahem…” coughed the Ghost of Quantum Past loudly. “Oh right, I’m not supposed to tell you about that. Time paradoxes and stuff, you know how it is” said the Ghost of Quantum Future. “But anyway, you should probably be getting back to your time! There are some people who are waiting for you!”

He started waving goodbye and the room around Sophie started filling with a now familiar haze.

“But wait” she yelled,” I have so many questions!” But as she spoke she felt the world dissolving around her and she started falling through the newly created darkness.

She woke up lying flat on the floor. Her notes were scattered all about her and a pen was painfully pressing into her left arm. “I must have fallen asleep” she thought, “was it all just a dream then?” She started gathering her notes, sighing at the work that still needed to be done when she heard a ghostly voice coming seemingly from nowhere.

“It wasn’t a dream Sophie, I hope you have learned something from our little trip. Also, please call your grandmother and tell her you’ll be right there. Your work can wait until after Christmas. Gooodbyeeeee.”

From all of us in the QuTech blog we wish you all a Merry Christmas and a Happy New Year!